Function percent_of_time(start_operation, end_operation, start_date, end_date)

' start operation     july 1 2014
' start date          jan 1 2013
' end date            dec 1 2013

If start_operation > start_date Then
    before_start = 1
    ratio = 0
'    ratio = 1
End If

' start               sept 1 2013
' start date          jan 1 2013
' end date            dec 1 2013

If start_operation >= start_date And start_operation < end_date Then
     patial_start = 1
     ratio = (end_date - start_operation + 1) / (end_date - start_date + 1)
     
'     If start_operation = start_date Then
'         ratio = (end_date - start_operation - 1) / (end_date - start_date + 1)
'         ratio = 2
'    End If


'     ratio = 2
End If
     
' start               sept 1 2012
' end                 sept 31 2020
'
' start date          jan 1 2013
' end date            dec 1 2013
     
     
If start_operation <= start_date And end_operation > end_date Then
     full_period = 1
     ratio = 1
'     ratio = 3
End If

' start               sept 1 2012
' end                 sept 1 2020
'
' start date          jan 1 2012
' end date            dec 1 2012

'
' Partial period at end
'

If end_operation >= start_date And end_operation <= end_date Then
     partial_end = 1
     ratio = (end_operation - start_date + 0) / (end_date - start_date + 1)
'     ratio = 4
End If

' start               sept 1 2012
' end                 sept 1 2020
'
' start date          jan 1 2013
' end date            dec 1 2019

If end_operation < start_date Then
     After_end = 1
     ratio = 0
'     ratio = 5
End If

percent_of_time = ratio

End Function
